The present invention relates to a process for the preparation of a woven fabric of low air permeability having a fine texture of excellent feeling which comprises extra fine fibers.
Processes for preparing a woven or knitted fabric of low air permeability having a fine and dense texture made from extra fine fibers are now publicly known. For example, Japanese Patent Application Laying-Open No. 63071/81 discloses a method which comprises preparing a woven or knitted fabric of fine texture from composite fibers of an islands-in-sea type, followed by treatments of removing the sea component and also making the fibers water and oil repellent. However, in case where composite fibers of an islands-in-sea type are used, a woven fabric of sufficiently low air permeability is not always obtained because of the decrease in the total cross-sectional area of the filaments as a unit resulting from the removal of the sea component from the composit fiber. Also, Japanese Patent Application Laying-Open No. 154546/81 discloses a method for preparing a highly dense knitted fabric by use of a composite fiber of a fibrilliform type comprising polyamide and polyester having a single fibrillose filament size of 0.5 denier or less after the fibrillation of the composite fiber. However, it does not necessarily follow that this method is an easy one from an industrial viewpoint since the method includes the use of benzyl alcohol of high concentration (30%) as an agent for the fibrillation of the composite fiber and also the steam treatment at 65.degree. to 100.degree. C. for the fibrillation.